function Snake(el) {
    this.el = el
    // 蛇长度
    this.len = 20
    // 存蛇
    this.snakeObj = [
        { x: 3, y :2, color:'red', el:null},
        {x: 2, y :2, color:'blue', el:null},
        { x: 1, y :2, color:'blue', el:null}
    ]
    this.direction = 'right'
}
Snake.prototype.remove = function() {
    for (let i = 0;i<this.snakeObj.length;i++){
        if(this.snakeObj[i].el){
            this.el.removeChild(this.snakeObj[i].el)
        }
    }
}
Snake.prototype.create = function() {
    this.remove()
    for (let i = 0;i<this.snakeObj.length;i++){
        // 创建对象
        let divObj = document.createElement('div')
        // 设置宽高 坐标 颜色
        divObj.style.width = this.len + 'px'
        divObj.style.height = this.len + 'px'
        divObj.style.position = 'absolute'
        divObj.style.left = this.snakeObj[i].x * this.len + 'px'
        divObj.style.top = this.snakeObj[i].y * this.len +'px'
        divObj.style.background = this.snakeObj[i].color
        this.snakeObj[i].el = divObj
        this.el.appendChild(divObj)
    }
}
Snake.prototype.move = function() {
    for(let i = this.snakeObj.length-1;i>0;i--) {
        this.snakeObj[i].x = this.snakeObj[i-1].x
        this.snakeObj[i].y = this.snakeObj[i-1].y
    }
    switch(this.direction) {
        case 'top':
            this.snakeObj[0].y -= 1
            break;
        case 'bottom':
            this.snakeObj[0].y += 1
            break;
        case 'left':
            this.snakeObj[0].x -= 1
            break;
        case 'right':
            this.snakeObj[0].x += 1
            break;
    }


    // for(let i = 0; i<this.snakeObj.length; i++) {
    //     if(this.snakeObj[i]){
    //         this.snakeObj[i].x += 1
    //     }
    // }
    this.create()
}